westcliffe01
Well-Known Member
Hitting low with tumbling bullets should be obvious. The BC is only valid with the pointy end going downrange. The drag on a tumbling bullet will obviously be much higher..
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Flabergasted and dumbfounded
- Thread starter johnnyk
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royinidaho
Well-Known Member
Your Flabbergasted and dumbfounded!!! That's exactly where I was a couple of months ago. I'm all grins and giggles because as you recall, misery loves company.
I was working up a drop chart for my 270 Allen Mag, its second barrel, right at 500 round count.
Shooting 169.5 Wildcats out of a 28" 8 twist, 3 groove Lilja @ 3350 FPS MV.
Two shots @ 0.25 MOA @ 300 and a good zero.
Two shots @ 0.5 MOA @ 580. Drop agreed with 1/2 MOA of computer. No adjustment made. Noted in shot log.
Two shots < 1 MOA @ 890. Again w/in 1/2 MOA of computer. Noted in shot log for later Shooter tweek.
Two shots @ 1100. Both missed the paper backer. Saw no dust.......
Another shot, no hit, no dust....
All shots video'd. Could see trace almost to the target.
Took a 4' x 4' piece of cardboard for a larger backer. One that I couldn't miss.
Couldn't hit it with a fairly good number of shots. What's with this?
Not real good reason could be determined. The first barrel went at 900 rounds. This one had only 500. Should have been able to validate drops and harvest game for years. I thought.
The target was a heavy gong suspended by two 6" wide pieces of rubber conveyor belting.
Later when moving the gong something stabbed my finger. Guess what. A perfectly formed, except for rifling marks, a 169.5 grain wildcat bullet had penetrated only one of the double straps with only a very very slightly deformed meplat sticking through the second layer of strap.
I don't get it. Somewhere beyond 890 yards those bullets were going bonkers and losing enough velocity that a fella could catch them with a baseball glove.
This seemed impossible to me especially when starting at over 3300 with a bc of well over 0.70.
Checked the throat. Guess what......GONE! Not a bad as the 900 round barrel but definitely gone.
Solution - I took a hacksaw to it about 1/2 down to keep from wasting time, money and attitude dink'n with it.
The bullet was in perfect shape with no deformation of the rifling imprints. An 8 twist?
I have no idea of why a complete lack of rifling for a couple of inches would do such a thing....
Good luck!
I was working up a drop chart for my 270 Allen Mag, its second barrel, right at 500 round count.
Shooting 169.5 Wildcats out of a 28" 8 twist, 3 groove Lilja @ 3350 FPS MV.
Two shots @ 0.25 MOA @ 300 and a good zero.
Two shots @ 0.5 MOA @ 580. Drop agreed with 1/2 MOA of computer. No adjustment made. Noted in shot log.
Two shots < 1 MOA @ 890. Again w/in 1/2 MOA of computer. Noted in shot log for later Shooter tweek.
Two shots @ 1100. Both missed the paper backer. Saw no dust.......
Another shot, no hit, no dust....
All shots video'd. Could see trace almost to the target.
Took a 4' x 4' piece of cardboard for a larger backer. One that I couldn't miss.
Couldn't hit it with a fairly good number of shots. What's with this?
Not real good reason could be determined. The first barrel went at 900 rounds. This one had only 500. Should have been able to validate drops and harvest game for years. I thought.
The target was a heavy gong suspended by two 6" wide pieces of rubber conveyor belting.
Later when moving the gong something stabbed my finger. Guess what. A perfectly formed, except for rifling marks, a 169.5 grain wildcat bullet had penetrated only one of the double straps with only a very very slightly deformed meplat sticking through the second layer of strap.
I don't get it. Somewhere beyond 890 yards those bullets were going bonkers and losing enough velocity that a fella could catch them with a baseball glove.
This seemed impossible to me especially when starting at over 3300 with a bc of well over 0.70.
Checked the throat. Guess what......GONE! Not a bad as the 900 round barrel but definitely gone.
Solution - I took a hacksaw to it about 1/2 down to keep from wasting time, money and attitude dink'n with it.
The bullet was in perfect shape with no deformation of the rifling imprints. An 8 twist?
I have no idea of why a complete lack of rifling for a couple of inches would do such a thing....
Good luck!
Lefty7mmstw
Well-Known Member
I had that happen a few years back with my 300win deer hunting. I pulled up on a white-tail at about 200 paces.... Pull, miss... What, it's a chip shot??? Pull again, miss.... walk forward a few paces to where I could shoot without anything at all in the way ( first shots were over a bit of a grassy rise).... bang, flop.... I didn't see a single blade of grass in the scope, but the bullets were hitting the dirt before the critter.
johnnyk
Well-Known Member
Well, I'm still not sure what the problem is. Been checking around with some of my friends/gunshops to see if anyone has a bore scope. It's possible the barrel is shot; it is a 6.5-284, I do run it at the upper limit of pressure and I have 700 rounds through it. Jury's still out. JohnnyK.
Have you checked and compared seating depth to the lands? This is generally a good indication of the barrel being shot our since it erodes from the throat. I would think if the barrel was worn enough to tumble bullets you would likely see a difference in leade.
Barrel crown OK?
If the problem persists, you could try Tubbs Final Finish system. I've been tempted to use it with some of my former barrels but always decided to rebarrel instead.
royinidaho
Well-Known Member
I used the Tubbs FF on the original 270 AM barrel. The Tubbs FF definitely brought the barrel back to it's at least 0.5 MOA ....... for exactly 20 shots. Then Kaput for sure!
I used the Tubbs FF on the original 270 AM barrel. The Tubbs FF definitely brought the barrel back to it's at least 0.5 MOA ....... for exactly 20 shots. Then Kaput for sure!
Yeah, that's what I was afraid of .
johnnyk
Well-Known Member
Checked the crown and that appears good but on the seating depth; something's amiss.
Back in July 2013 my journal shows 2.5550" as the seating depth for the 140gn A-Max.
Just checked it again and I'm getting 2.5425". That's .0125" shallower. Could that be "the" carbon ring?
I have noticied that the necks of the Lapua cases were getting excessively smutey after firing and I planned on annealling them all this time after all the prepping was done.
Not sure I want to do the Tubb's FF. I have some IOSSO paste and a friend suggested JB's Bore paste and I read JB's and Kriol was good for the hard crude in barrels. Anything else? JohnnyK.
Back in July 2013 my journal shows 2.5550" as the seating depth for the 140gn A-Max.
Just checked it again and I'm getting 2.5425". That's .0125" shallower. Could that be "the" carbon ring?
I have noticied that the necks of the Lapua cases were getting excessively smutey after firing and I planned on annealling them all this time after all the prepping was done.
Not sure I want to do the Tubb's FF. I have some IOSSO paste and a friend suggested JB's Bore paste and I read JB's and Kriol was good for the hard crude in barrels. Anything else? JohnnyK.
You might try Wiipe Out. I recently cleaned up an old rifle that had about 50 years worth of crud in the barrel. The bore looked like a mirror. It is very effective with carbon removal.....
royinidaho
Well-Known Member
900 on barrel 1 and 500 on barrel 2.....
johnnyk
Well-Known Member
"If you have a different lot# of Amaxs then the measurement will most likely change. Copy?"
Yeah, I know what you mean. Taking a hard look at my A-Max's, not sure they're all I thought they were. My shooting buddy tried them today for the first time in his .308. He told me he shot a 4.5" group with them today at 1000yds, 5" @ 1100yds but they were about 14-16" at 1200yds. I figured his .308 was likely going sub-sonic.
I started cleaing my barrel last night with Hoppes Bore Cleaner. I ran a ton of patches through it with various sized nylon brushes. Additionally, I used ammonia to remove any copper. Started on it again shortly after eating Raisin Bran. More Hoppes and also used some BlueMagic Metal Polish Cream I had. Not sure how it looks on the inside, will try to find a borescope this week.
Thanks to all for your assistance, experiences and information. I will let you know what comes of all this. Hopefully the outcome will be favorably and a learning experience for all. JohnnyK.
Yeah, I know what you mean. Taking a hard look at my A-Max's, not sure they're all I thought they were. My shooting buddy tried them today for the first time in his .308. He told me he shot a 4.5" group with them today at 1000yds, 5" @ 1100yds but they were about 14-16" at 1200yds. I figured his .308 was likely going sub-sonic.
I started cleaing my barrel last night with Hoppes Bore Cleaner. I ran a ton of patches through it with various sized nylon brushes. Additionally, I used ammonia to remove any copper. Started on it again shortly after eating Raisin Bran. More Hoppes and also used some BlueMagic Metal Polish Cream I had. Not sure how it looks on the inside, will try to find a borescope this week.
Thanks to all for your assistance, experiences and information. I will let you know what comes of all this. Hopefully the outcome will be favorably and a learning experience for all. JohnnyK.
